This game is incredibly easy. I had a hero w/ Trainee and Archwizard as their units... upped Hero's magic use stat to 30 and creatures rarely even make it 2 steps into the map.
Ok, after much frustration... engine 30, shield 100, weapon 80+, beat game. I went weapon to like 41 early, then shield to 100, then engine to 30, then all weapon until end. Good luck on the badge.
Extremely easy w/ Darkness Energy Recharger and Ultra Bomb from legendary shop... sit there nuking and dodging constantly and then just recharging your energy in like 10 seconds... bosses can barely shoot through all the nuke push.
I won on 10 by just making a push for water control... I managed to get 2 cruisers out there and then just held then off w/ stealth tanks while my cruisers pounded their static defenses... needed planes too to defend cruisers from hindenbergs
After experiencing the game in it's entirety, it's a pretty neat game. Good story/concept. Only problem is the story/concept is not clear at all if you're not paying close attention or just futzing around with the game to start.